Author Topic: Mixing table on MIC input ?  (Read 699 times)

tadkozh

  • New to the forum
  • *
  • Posts: 2
Mixing table on MIC input ?
« on: June 28, 2022, 10:50:27 PM »
Hello !

I want to shoot the show of my son's classroom on my 550D. It is the town's theater  8).
I spoke to sound engineer, he is able to output me a line from his mixing table (R+L).
My question is : is my DSLR able to input a powered waveform from the mixing table, or it's only for microphones ?

Thanks for your help

PS : I already google this research, but didn't found interesting things, and sorry for my English... I'm French  :P

yokashin

  • Member
  • ***
  • Posts: 120
Re: Mixing table on MIC input ?
« Reply #1 on: June 29, 2022, 05:18:07 AM »
I have recorded several school concerts and performances. At concerts, I put the camera on a tripod next to the console and recorded with built-in microphones. During the performances, I placed between the console and the stage (among the audience). With the auto mode, the recorded sound was always ok.
I think there may be little audible applause from the console ...

Regards
70D.112 [main cam] | M.202 | S110 [CHDK]

Walter Schulz

  • Contributor
  • Hero Member
  • *****
  • Posts: 8423
Re: Mixing table on MIC input ?
« Reply #2 on: June 29, 2022, 08:17:32 AM »
AFAIK there is no problem. It is common practice to use audio recorder output as audio source.
You can tell your sound engineer your DSLR has a high input impedance (> 10 kOhm).
Put your audio on manual and adjust recording level together with him.

Disclaimer: 550D's input amplifiers are considered to be mediocre. If you want to have best clean audio you may want to use another recording device and use cam's audio just for syncing.

PS: Your 550D is among the few cameras able to do audio monitoring (headphone) with some wiring.

Skinny

  • Member
  • ***
  • Posts: 197
Re: Mixing table on MIC input ?
« Reply #3 on: June 29, 2022, 10:55:35 AM »
There shouldn't be any problem, I used 550D with pro audio equipment many times. Surprisingly, it can handle line levels, at least consumer -10dBu standard level. Sound engineer will probably give you a stereo cable from -10dBu output of a mixer, you can record stereo and not just r+l.

Make sure you *disabled* mic power and selected "external stereo" on the audio page. Set analog gain to 0db, turn off any digital gain or AGC. And before recording, check these settings again because sometimes they can reset on 550D, I don't know why.

Stay away from clipping obviously, even from yellow indicators on your camera. yellow means there is too little headroom if something goes even slightly louder.
And if the level will be too high for some reason - ask for the headphone output where the volume could be set lower..

But in order to clip 550D connected to -10dBu output the mixer should run at yellow zone (close to zero or +3 +6) on it's meters, which probably won't happen. In real life I usually see sound guys use levels way low than too high.


p.s. 10k is relatively low impedance, it is somewhat standart impedance for modern consumer line-level audio inputs.. it's absolutely ok. lower than 10k could be a problem sometimes with old equipment, old consumer stuff was designed for even ~50k or so.
and 550D's pres... they may be not that great, but when you set analog gain to zero it is not that important. Because even cheap op-amps at unity gain usually perform relatively well for typical audio needs..


By the way, I think Canon engineers actually designed the audio curcuit around -10dBu standart but never gave us a way to disable stuff like additional gain and AGC.
I can check actual levels (with sine wave and multimeter) 550D and 5D2 can handle, and whether it is close to the standard or not. It feels like that, although I never checked.

tadkozh

  • New to the forum
  • *
  • Posts: 2
Re: Mixing table on MIC input ?
« Reply #4 on: June 29, 2022, 05:18:29 PM »
Hello,

Thanks for your advices.
I've made some tests today : it connected my CD player output to the MIC input (AGC disabled, External forced, Gain to 0). I am sometimes in the yellow (even red) audio indicator. However the sound looks good. But I will ask the sound engineer to come down the volume from the mixing table.
Now, I will look at the duration issue : at 1080p, the time is limited to about 10 minutes, I will test the auto-restart ML functionality, but I think I'll have a little cut...